The present invention relates generally to wafer furnaces and, more particularly, to a system and method for monitoring wafer furnace production efficiency.
Wafer furnaces are used for numerous processes in the manufacture of semiconductor devices. For example, ion implantation and wafer annealing processes are performed in a wafer furnace. Wafer furnaces can process individual wafers or in batches of wafers depending on the particular wafer furnace design and semiconductor process requirements.
Like most semiconductor processing equipment, wafer furnaces often operate nearly continuously in a production line environment. Wafer throughput per hour (WPH) is a very closely monitored performance metric of the wafer furnace. The WPH can be used to identify semiconductor manufacturing process choke points and other less than optimum conditions in the wafer furnace. Typically, the wafer furnace includes a control system that includes preprogrammed operations that the wafer furnace will automatically perform on the wafers that are loaded into an input portion of the wafer furnace.
A wafer furnace operator typically monitors wafer furnace operations. The wafer furnace operator may also be responsible for loading wafers to be processed in the input portion of the wafer furnace and unloading processed wafers from an output portion of the wafer furnace. A furnace operator typically observes the processing of multiple batches of wafers through a wafer furnace during a single operator's working shift. A furnace operator may also perform manual functions and adjustments to the wafer furnace. In addition, a furnace operator may manually process wafers through the wafer furnace.
The overall performance of the wafer furnace as identified by the WPH (wafer throughput per hour) is often monitored to ensure the wafer furnace throughput meets acceptable performance ranges. However, typical WPH monitoring systems cannot differentiate automatic wafer processes from manual operations or operator errors such as misleading wafers in the input portion of the wafer furnace. Typical WPH monitoring systems aggregate multiple batches or lots of wafers that are processed through the wafer furnace to determine the WPH metric.
In view of the foregoing, there is a need for accurate monitoring of the wafer throughput per hour of a wafer furnace.